ColorLock internals

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Variant1
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ColorLock internals

Unread postby Variant1 » Fri Nov 03, 2017 1:45 am

Hi!

What capacitor inside ColorLock? The small SMD. Mine is broken. I go to shop, they told me there are around 800 different capacitors of the same size.
What order of color layers: green, blue, yellow?

robespierre
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Re: ColorLock internals

Unread postby robespierre » Fri Nov 03, 2017 2:32 am

Small SMD capacitors are rarely marked in any useful way. The only means of replacing it are
1) Taking a working unit, removing the capacitor, and measuring it
2) Guessing a value from the schematic and putting one in
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Variant1
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Re: ColorLock internals

Unread postby Variant1 » Fri Nov 03, 2017 6:21 am

Obviously, I don’t have nor schematics nor another unit, so both methods are unacceptable. Better I hope to find here SGI retired engineer, for example. Or support centre tech staff. Who have knowledge. Buying another to fix this—no, because it is for collection, not for work, but I want my collection in working state,

robespierre
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Re: ColorLock internals

Unread postby robespierre » Fri Nov 03, 2017 6:34 am

I have not seen the circuit board in the ColorLock, but simple devices have simple schematics, which can be reconstructed in single-digit hours of time, with the right approach. Sometimes the value is not critical, but knowing this depends on its role in the circuit. For example, by knowing that the capacitor connects between Vdd and Ground, it must provide bypass for a nearby transistor or IC, and the value can be anything that will smooth out its switching noise. Capacitors used in timing or tank circuits are more value critical, but they also tend to be different color ceramic (white) because of its superior properties.
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Irinikus
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Re: ColorLock internals

Unread postby Irinikus » Fri Nov 03, 2017 6:49 am

When I received my 400MHz R12K module for my O2, there was a large surface mount cap on the back of the module that was cracked, as the person who sold it to me had obviously removed the heatsink from the module to look at the CPU itself and had replaced the securing bracket incorrectly when reassembling the module, this resulted in the cap sitting under the securing bracket and the resulting pressure causing it to crack.

I was devastated when I saw this, as you know, these modules are quite expensive and this one was now damaged. (I luckily picked it up before installing it in my O2.)

I had no idea what the value of the cap was but, I took a chance and removed a cap that looked the same from an R10K module that I had lying around and replaced the broken cap with it. (Knowing that not all of the values of caps in a circuit are critical)

The module now works perfectly!

Try to fix it by replacing the cap with another that looks the same, it's a good place to start.

If this doesn't work then look for another solution.
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Variant1
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Re: ColorLock internals

Unread postby Variant1 » Fri Nov 03, 2017 6:56 am

There are no board. Only three wires from the sensor and a capacitor between wires.
I have no idea about this schematics and even don’t know how to try. It is a precious device, I doubt I can solve the problem myself.

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Irinikus
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Re: ColorLock internals

Unread postby Irinikus » Fri Nov 03, 2017 6:58 am

Take a picture, as this my help someone here to give you advice.
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Image Image; Image........... Image; Image... ImageImage Image.... Here they are: :arrow:

Variant1
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Re: ColorLock internals

Unread postby Variant1 » Fri Nov 03, 2017 12:46 pm

Maybe. Please look.

Image Image

robespierre
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Re: ColorLock internals

Unread postby robespierre » Fri Nov 03, 2017 1:17 pm

the device appears to be a dual phototransistor, and the capacitor is between the shared collector and one of the emitters
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Variant1
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Re: ColorLock internals

Unread postby Variant1 » Fri Nov 03, 2017 5:10 pm

So, is it possible to determine its capacity?

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Irinikus
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Re: ColorLock internals

Unread postby Irinikus » Fri Nov 03, 2017 9:32 pm

It appears to be a bypass or noise filtering cap as its placed between one of the inputs (or outputs ) and the shielding of the cable (ground).
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Image Image; Image........... Image; Image... ImageImage Image.... Here they are: :arrow:

Variant1
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Re: ColorLock internals

Unread postby Variant1 » Sat Nov 04, 2017 1:07 am

Irinikus wrote:It appears to be a bypass or noise filtering cap as its placed between one of the inputs (or outputs ) and the shielding of the cable (ground).

Maybe, I thought about something like this myself. However, I am not a pro in electronics and this knowledge does not help me to replace the cap :(

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Irinikus
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Re: ColorLock internals

Unread postby Irinikus » Sat Nov 04, 2017 1:17 am

For now, try replacing the cap with another of the same physical size and see if the ColourLock works, the unit won't bow, as the cap will only allow DC to flow until it's fully changed and that would be for a couple of nano or picoseconds in this case.
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Image Image; Image........... Image; Image... ImageImage Image.... Here they are: :arrow:

Variant1
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Re: ColorLock internals

Unread postby Variant1 » Sat Nov 04, 2017 1:58 am

Irinikus wrote:For now, try replacing the cap with another of the same physical size and see if the ColourLock works, the unit won't bow, as the cap will only allow DC to flow until it's fully changed and that would be for a couple of nano or picoseconds in this case.

Do you want to say that its capacity is not important in that case, and I can set capacity as much as possible?

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Irinikus
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Re: ColorLock internals

Unread postby Irinikus » Sat Nov 04, 2017 2:08 am

In this case I don't think that its important.

The thing that's important however, is the voltage rating of the cap (make use of one with a slightly higher voltage rating than the rail voltage of the system that its hooked up to).

As for value, I would go with a value that is average (middle of the road) for a cap of that form factor for the moment (not to big or not too small).

See if it works and then take it from there if it doesn't.
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Image Image; Image........... Image; Image... ImageImage Image.... Here they are: :arrow:


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